Window frames traditionally have been made from wood or metal or various combinations of wood and metal. In recent years, windows with hollow polymer frames are becoming more popular because of improved thermal properties, lower cost and relative ease of manufacture, assembly and installation compared with wood and metal windows. As used herein, the terms "polymer" and "polymeric" refer to window components in which a polymer such as polyvinyl chloride is the principal constituent. Such components may also contain various other ingredients such as fillers, glass reinforcing fibers, processing aids and impact modifiers. All window assemblies are limited in size by the requirement that they withstand design windloads as established by local building codes and ordinances. Windloads, window sizes and window glass thickness are factors in determining whether maximum deflection of the window assembly exceeds 1/175 of its length when subjected to the design load, as set forth in ASTM E-1300. Also included in the requirements is a maximum allowable deflection of 0.75 inch regardless of the window length. Accordingly, there is a need to provide polymer windows with reinforcements so that they are able to withstand design windloads when several such windows are combined into a unitary assembly.
Windows made from various combinations of polymer and metal components are known in the prior art. However, these prior art windows generally suffer from one or more serious disadvantages making them less than entirely suitable where large windloads are encountered or where the windows have an unusually large size. For example, Mennell U.S. Pat. No. 3,302,354, describes a window assembly having an exterior frame made from extruded aluminum sections and an interior frame formed of sections of extruded vinyl material. Kessler U.S. Pat. No. 3,918,231, claims a window frame construction comprising a metal frame having extruded aluminum members covered on its interior side by extruded plastic members. Windows shown in the Mermell and Kessler patents perform adequately as single units, but they do not possess sufficient strength and rigidity to withstand extreme windloads or to be combined into large multi-unit assemblies.
A principal objective of the present invention is to increase the rigidity of a window assembly.
A related objective of the invention is to provide a metal reinforcement for enhancing the rigidity and stability of a window assembly.
Another objective of the invention is to provide a securement means for anchoring the window assembly to a support structure surrounding a window opening in a building.
Additional objectives and advantages of our invention will become apparent to persons skilled in the art from the detailed description that follows.